Existing erectile dysfunction implants typically use manually operated pumps and reversing switches implanted in the scrotum to transfer fluid back and forth between inflatable cylinders implanted in the penis and a fluid reservoir implanted in the abdomen. Some patients, particularly older people with arthritis, find it difficult to operate the pump and switch, and, therefore, may elect not to have the implant.
Existing artificial urinary and anal sphincters implants use continuous passive pressure from a fluid reservoir implanted in the abdomen to inflate cuffs implanted around the urethra or anus. To operate, the patient depressurizes the cuff by manually depressing a pump, implanted in the scrotum for men and the labia for women, to transfer fluid from the cuff back to the reservoir. The cuff then repressurizes automatically to achieve continence. Like the penile implant, manual pump operation may be difficult, especially for women, where the pump's location makes operation difficult, may cause chronic discomfort and may limit activities such as bicycle riding.
Additionally, current artificial sphincter lifespans may be limited by tissue atrophy. This common complication is likely caused by cuff dynamics, where constant pressure is applied to the biological structure over long time periods, and may be worsened by tissue frailty due to aging and cancer radiation treatments.
More recent implant concepts may replace the manual pump with an electrically driven pump and reversing switches which may be controlled and powered from an external source. In operation, an external unit may send wireless control signals to an internal unit, which then activates the pump. In certain systems, the internal control unit and pump are powered by an internal source, such as batteries. In others, external power may be transmitted transdermally by close-coupled magnetic induction, which forms an air core electrical transformer.
A recent erectile dysfunction implant concept replaces the manual pump with a transdermal close-coupled magnetic induction powered solenoid driven pump, analogous to a powered hypodermic syringe, to provide inflation and deflation. However, these devices may be limited because the solenoid pump implant is much larger than the manual pump implant's reservoir, as the solenoid must move out from the reservoir by as much as it moves in. Additionally, these devices may be MRI-unsafe because the solenoid's iron core may translate and rotate from MRI's magnetic fields, and may heat from the MRI's radio frequency (RF) field.
Another recent implant concept for erectile dysfunction and urinary and fecal incontinence replaces the manual pump with an electric motor and pump or a nonmagnetic piezoelectric motor powered transdermally by close-coupled magnetic induction and external to internal control signals. These devices are limited because under leak conditions, the motor will run continuously until power is exhausted and the piezoelectric motor may produce limited pumping force at single digit efficiency resulting in slow operation and excess heating. Additionally, the coupling of the piezoelectric motor to the pump, complicated motor drive electronics and the use of powered valves may be volume intensive, of lower reliability and MRI-unsafe.
Furthermore, these devices transmit power transdermally by close coupled magnetic induction, which forms an air core electrical transformer with its primary winding external to the patient and its secondary winding internal to the patient. Due to the low permeability of air and body tissue, magnetic flux linkages between these primary and secondary windings are not concentrated like they are in an iron core transformer. Therefore the implanted transformer secondary must be implanted in the dermis, a millimeter from the transformer's external primary placed over the skin, a physically and cosmetically uncomfortable situation. Additionally, the amount of transdermal power that can be safely transferred is limited due to heating caused by the primary winding's strong electric field, which results from needing to magnetically transmit power through air and tissue.
Also, physician changing of preset inflatable implant pressures is an invasive procedure; they offer no implant performance monitoring by the patient or physician; they have no means of relieving cylinder or cuff pressure should the implant fail; they address only one dysfunction at a time; and they do not allow for implant performance analysis across many patients.
What is needed is a compact, easy to operate apparatus that is programmable, MRI-conditional and can treat multiple dysfunctions with one implant. A device is needed that can transmit sufficient power and bidirectional communications signals over longer distances, relieve cylinder and cuff pressure upon implant failure, not invade the labia or scrotum, increase artificial sphincter lifespan, and allow analysis of data across patients.